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  <script>

    function Foo() {
      // 1.创建空的对象
      // 2.将Foo的prototype原型(显式隐式)赋值给空的对象的__proto__(隐式原型)
    }

    console.log(Foo.prototype)

    var f1 = new Foo()
    var f2 = new Foo()
    var f3 = new Foo()
    var f4 = new Foo()
    var f5 = new Foo()
    console.log(f1.__proto__)
    console.log(f1.__proto__ === Foo.prototype) // true
    console.log(f3.__proto__ === f5.__proto__) // true

  </script>

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